A spectrophotometer, a device which measures the intensity of light at its component wavelength(s), is often used to determine characteristics of specimens (usually liquid specimens) in laboratory and other settings. Light, usually in the ultraviolet (UV) and/or visible (Vis) wavelength ranges, is directed through a specimen, and the intensity of the output light at its component wavelengths is compared to the intensity of the input light at its component wavelengths to determine optical characteristics of the specimen (such as absorbance, transmittance, and/or reflectance). One type of spectrophotometer, a fluorescence spectrometer (also known as a spectrofluorometer or fluorospectrometer), also compares input and output light from a specimen, but does so to detect fluorescence, i.e., the emission of light from the specimen at one or more wavelengths owing to the specimen's absorption of light at other (typically shorter) wavelengths. The various measured characteristics—fluorescence, absorbance, transmittance, reflectance, etc.—can then provide information about the identities of the components within the specimen, their relative concentrations, and other features of the specimen.
Spectrophotometers for analysis of small specimens—e.g., specimens having a volume of 2 microliters or less—are becoming increasingly popular owing to their value in the fields of biotechnology and pharmacology, where specimens often tend to be available in very limited quantities. Such spectrophotometers pose design challenges because the small specimen size offers little room for light emission and collection components, and tends to limit the versatility of the spectrophotometers. Some solutions to these challenges are presented in U.S. Pat. Nos. 6,628,382; 6,809,826; and 7,397,036, as well as International (PCT) Patent Application WO2007111838, but it would nonetheless be useful to have spectrophotometers and/or spectrophotometer components (and more generally photometers and/or photometer components) which offer further improvements in versatility.